When a man in California went to Hawaii last month, he said he didn’t have to worry about getting sick.
The flu was the only thing keeping him healthy.
That was until he came back to the United States with the virus.
“I was really concerned that I was going to get sick and have to cancel my trip,” he said.
The flu is the most common seasonal flu.
It can be fatal, and it can take up to a year for symptoms to appear.
It’s transmitted through direct contact with the respiratory virus, which usually affects the nose and mouth, and can cause pneumonia.
People can get flu during the spring, summer, and fall months.
People with weakened immune systems are at higher risk of developing complications like pneumonia and respiratory infection, according to the CDC.
It’s also very contagious.
It doesn’t take long for symptoms like cough, runny nose, and fever to appear and spread, said Dr. Christopher Pfeiffer, the chief medical officer for the American Public Health Association.
Pfeiffers lab tested 28 people with flu and found that three were negative for the virus, and three had symptoms of influenza.
That means more than one in every three people tested had flu, and two had the flu virus in their system.
“The risk of transmission is very high,” he told NBC News.
But people with weakened immunity can’t be tested before they travel.
Pfeifers said people who have weakened immune system should avoid traveling unless they have clear symptoms, have a confirmed influenza infection, and have a vaccination schedule in place.
He said if the virus can infect an unprotected individual in the United Kingdom, that person is at an increased risk of being infected in the U.S.PFEIFER said people with weaker immune systems could be more vulnerable to infection with the flu if they’re in hotels, eating at restaurants, and using the internet while traveling.
“If you’re not careful, you could be exposed to the virus,” he added.
If you’ve traveled overseas and have any questions about flu vaccinations, call your local public health center.